Spray nozzles having centrifugal swirl chambers upstream of the spray orifice have been employed for various uses, such as spray drying, aeration, cooling, and fuel injection. A typical such nozzle is illustrated in U.S. Pat. No. 3,680,793 to Tate et al. which shows in FIG. 1 a nozzle body, an orifice plate defining a spray orifice, and a swirl chamber block received within the nozzle body. A retainer member is threadedly engaged behind the swirl chamber block for retaining and positioning the swirl chamber and orifice plate within the nozzle body. For spray drying applications, fluid containing suspended and dissolved solids is supplied to the nozzle under pressures generally in the range of 500 p.s.i. to 5000 p.s.i. This mixture passes through the nozzle at high velocity, resulting in rapid wear to the swirl chamber block and orifice plate. Because of this rapid wear, the swirl chamber block and orifice plate may require frequent replacement.
In the design of the '793 patent, replacement of these worn components is difficult. In practice, one might place the retainer member on a flat surface with the end for retaining the swirl chamber block facing upwardly. One would then place the swirl chamber block into the recess formed in the end of the retainer member. Next, one would place the nozzle body on a flat surface with its inlet end facing upwardly and the orifice plate would be inserted into the counter-bore formed in the nozzle body. The next step would be either (i) to invert the retainer member and swirl chamber block and insert the inverted components into the nozzle body, or (ii) to invert the nozzle body and orifice plate, and place the inverted components over the retainer member and swirl chamber block. In either case, for the inverted parts, the wear component (either the swirl chamber block or orifice plate) would tend to fall out, thus making assembly extremely difficult.
Another possible assembly method would be to place the retainer member on a flat surface with its downstream end facing upwardly, and to place the swirl chamber block into the recess formed in the upwardly-facing end of the retainer member. Next, the orifice plate would be balanced on top of the swirl chamber block. Finally, the inverted nozzle body would be placed over the stack formed by the retainer member, swirl chamber block and orifice plate, and the nozzle body then would be threaded onto the retainer member. However, this final operation would be problematic because the orifice plate would tend to move during assembly, thus making it difficult to locate the orifice plate within the counter-bore formed in the nozzle body.
Accordingly, it is an object of the present invention to provide an improved spray nozzle, and improved wear components for such nozzles, including swirl units and orifice plates, which overcome the above-described drawbacks and disadvantages encountered in assembling prior art spray nozzles.